Windows pure shell build works

default.nix

@@ -12,9 +12,10 @@ let
   newBuildTarget = {
     nixPkgsSystem,
     rustTarget ? nixPkgsSystem,
-    depsBuildBuild ? pkgsCross: [],
+    nativeBuildInputs ? pkgsCross: [],
+    rustFlags ? pkgsCross: [],
   }: {
-    inherit nixPkgsSystem rustTarget depsBuildBuild;
+    inherit nixPkgsSystem rustTarget nativeBuildInputs rustFlags;
   };
 
   # centralize per-target configuration in a single place.
@@ -40,10 +41,10 @@ let
     "x86_64-windows" = newBuildTarget {
       nixPkgsSystem = "x86_64-w64-mingw32";
       rustTarget = "x86_64-pc-windows-gnu";
-      #depsBuildBuild = pkgsCross: [
-      #  pkgsCross.stdenv.cc
-      #  pkgsCross.windows.pthreads
-      #];
+      nativeBuildInputs = pkgsCross: [ pkgsCross.windows.pthreads ];
+      rustFlags = pkgsCross: [
+        "-C" "link-arg=-L${pkgsCross.windows.pthreads}/lib"
+      ];
     };
   };
 
@@ -143,11 +144,13 @@ let
   '';
 
   buildEnv = rec {
-    nativeBuildInputs = (buildTarget.depsBuildBuild pkgsCross) ++ [
+    nativeBuildInputs = (buildTarget.nativeBuildInputs pkgsCross) ++ [
       toolchain
       pkgs.protobuf
-      #pkgsCross.stdenv.cc
-      #pkgsCross.windows.pthreads
+
+      # Required for shell because of rust dependency build scripts which must
+      # run on the build system.
+      pkgs.stdenv.cc
     ];
 
     SODIUM_LIB_DIR = "${libsodium}/lib";
@@ -159,11 +162,11 @@ let
     CARGO_BUILD_TARGET = rustTarget;
     CARGO_BUILD_RUSTFLAGS = [
       "-C" "target-feature=+crt-static"
-      "-C" "link-args=-static"
+      "-C" "link-arg=-static"
 
       # https://github.com/rust-lang/cargo/issues/4133
       "-C" "linker=${TARGET_CC}"
-    ];
+    ] ++ (buildTarget.rustFlags pkgsCross);
   };
 
 in {
@@ -182,7 +185,7 @@ in {
     ];
   } // buildEnv);
 
-  shell = pkgs.mkShell buildEnv;
+  shell = pkgsCross.mkShell buildEnv;
 
   # TODO
   #clippy = {